S6368 Signet Ring Adenocarcinoma in Pregnancy: Balancing Maternal and Fetal Health in a Rare Diagnosis

Introduction: Signet ring cell carcinoma (SRCC) is a rare and aggressive subtype of adenocarcinoma, most commonly originating in the stomach but also found in the colon, breast, bladder, and pancreas. It tends to infiltrate the stomach wall rather than forming a discrete mass, making early detection difficult as patients present with nonspecific symptoms like epigastric pain, nausea, vomiting, and early satiety. SRCC is more common in younger patients and females compared to other gastric cancers. It is also associated with worse prognosis due to early lymphovascular invasion, peritoneal dissemination, and poor response to chemotherapy. Case Description/Methods: Our patient is a 31-year-old pregnant G5P1031 woman with a history of depression, gastroesophageal reflux disease, and nephrolithiasis who presented at 37 weeks gestation with acute on chronic abdominal pain and poor oral intake. She had longstanding epigastric pain, nausea, and vomiting predating her pregnancy, with a delayed esophagogastroduodenoscopy (EGD) due to conception. Imaging revealed distal stomach and proximal duodenal wall thickening concerning for gastroduodenal intussusception. Labs showed elevated liver enzymes, anemia, and thrombocytopenia. Given persistent symptoms and concern for intussusception, she underwent a C section followed by EGD, which showed severe gastric inflammation and mucosal changes concerning for eosinophilic esophagitis (EOE). Biopsies revealed poorly differentiated adenocarcinoma with signet ring cell in the gastric antrum and EOE. A staging computed tomography (CT) showed mass-like thickening of the gastric antrum, pyloric involvement, and enlarged lymph nodes with a dominant mesenteric node measuring 9 × 14 mm. Despite receiving 4 cycles of FOLFOX, she ultimately required a subtotal gastrectomy, omentectomy, and cholecystectomy. Her course was further complicated by peritoneal carcinomatosis with loculated ascites. Discussion: This rare and challenging diagnosis of SRCC in the setting of pregnancy presents significant diagnostic and therapeutic dilemmas. This aggressive subtype is often diagnosed at an advanced stage due to nonspecific symptoms which could be misattributed to pregnancy. In pregnant patients, imaging and endoscopic evaluation can be further delayed. Management requires a multidisciplinary approach to balance both maternal and fetal health, often requiring an early delivery. Prognosis is typically poor, underscoring the importance of maintaining a high index of suspicion in pregnant patients with persistent gastrointestinal symptoms.